1. The present invention relates to an image forming apparatus. More particularly, it relates to a technique of forming a toner image on an image bearing member.
2. Description of the Related Art. Conventionally, in an image forming apparatus disclosed in the Japanese Unexamined Patent Publication No. 2005-164676, when a printing rate (a ratio of dots bearing toner particles with respect to all dots in print image data) of an image on a recording sheet is high, a time length after forming of a toner image onto a recording sheet until starting of the next toner image forming is made long, thereby controlling a start timing of the next toner image forming is controlled to be delayed. In this delay control, when a printing rate is high, a delaying time in accordance with the printing rate is read out from a predetermined storing section. A time which is calculated by adding the read delaying time to a default value is set to be the toner image forming start timing for the next toner image forming. In an image forming apparatus adopting the electrophotographic method, there has been a problem that intensity of a toner image formed on a developing roller is lightened when toner particles of a toner layer formed on a developing roller are rapidly consumed. This is because conveyance of toner particles are delayed, and enough amounts of toner particles cannot be supplied from a magnetic roller. However, the image forming apparatus disclosed in the Japanese Unexamined Patent Publication No. 2005-164676 solves the above-described problem by delaying an image forming to not to lighten an intensity of a toner image.
However, in the image forming apparatus disclosed in the Japanese Unexamined Patent Publication No. 2005-164676, waste of work has been generated in a processing requiring calculation of a delaying time since the calculation of delaying time in the above-described toner image forming is performed each time when the printing rate is high.